Humans shouldn't colonize mars. The reason people would go there is because humans have trashed our planet so badly. If people want a new planet they can help fix the one they and the ancestors ruined. You don't deserve a new chance if you don't have a good background to back you up. For example, if you tell a person who lies and can't keep a secret ever a secret. Lets say they tell someone. Why would you give them another chance if you know they just lie. Same thing goes for going to mars. Why give humans another planet if they will just ruin that one too?